JPH0432150A - High pressure metallic vapor discharge lamp - Google Patents

Abstract

PURPOSE:To suppress the temperature rise of an infrared reflecting film, and to prevent the thermal deterioration of the infrared reflecting film, as well as the deterioration of an external tube by making the outer surface of an intermediate tube on which the infrared reflecting film is formed, abut on the inner surface of the external tube almost over the entire surface. CONSTITUTION:An intermediate tube 10 is stored in an external tube 1, and, since the infrared reflected by an infrared reflecting film 11 pass through the tube, the temperature of the intermediate tube 10 is raised to a much higher level, even when it is suppressed not to reach no less than 500 deg.. The outer surface of the intermediate tube 10 is made to abut on the inner surface of the external tube 1 almost over the entire surface, and the heat of the intermediate tube 10 is discharged to the outside through the wall of the external tube 1. The temperature rise of the intermediate tube 10 as well as of the infrared reflecting film 11 is thus suppressed. The thermal deterioration of the infrared reflecting film 1 is thus prevented, and the blackening of the external tube 1 can be prevented, because no sprashing is generated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention (Field of Industrial Application) The present invention relates to a structure of a high-pressure metal vapor discharge lamp that is effective when applied to a high-pressure sodium lamp or the like.

(Prior art) For example, a high-pressure sodium lamp has electrodes sealed at both ends of a ceramic arc tube made of translucent alumina, etc., and inside contains sodium as a luminescent metal, mercury as a buffer gas metal, and a starting material. It is filled with a rare gas, and has a double tube structure with the arc tube housed in the outer tube, and has high luminous efficiency even among high-intensity discharge lamps.
It is attracting attention as a lamp suitable for energy saving.

In order to further increase the luminous efficiency of such high-pressure sodium lamps, it is effective to raise the temperature of the arc tube to increase the vapor pressure of sodium, and as the vapor pressure of sodium increases, the emitted light color gradually becomes heavier. There are advantages such as improved color rendering properties.

As a means of increasing the temperature of the arc tube during lighting, it has been proposed to reflect infrared rays emitted from the arc tube and return them to the arc tube, thereby warming the wall of the arc tube with the infrared rays. For example, since the red component of the emitted light is somewhat blocked, it is also possible to improve the color temperature.

In the conventional case, a film that transmits visible light and reflects infrared rays is formed on the outer surface of the outer tube (Japanese Patent Application Laid-open No. 101756/1983).
It has been known.

In other words, the infrared reflective film is formed of a metal oxide such as Ti0-5in2, but when this infrared reflective film is exposed to a high temperature of 500°C or higher in a vacuum or an atmosphere where oxygen exists, oxygen is lost in a short time. It has the property of sublimating. Therefore, when such an infrared reflecting film is formed on the outer surface of the arc tube bulb, oxygen scatters and adheres to the inner surface of the outer bulb, causing early blackening of the outer bulb.

For this reason, an infrared reflective film is formed on the outer surface of the outer bulb.

However, when an infrared reflective film is formed on the outer surface of the outer bulb, not only is the outer bulb heated by the infrared rays reflected by this reflective film, but the outer bulb, which is the base material for coating when baking the infrared reflective film, is Since the temperature rises to about 900° C., it is necessary to use quartz glass with excellent heat resistance as the outer tube. However, the outer tube made of quartz glass is difficult to process and expensive.

Therefore, a structure has been considered in which an intermediate tube made of quartz glass is disposed between the outer tube and the arc tube so as to surround the arc tube, and an infrared reflective film is formed on the outer or inner surface of this intermediate tube.

In this way, the infrared rays emitted from the arc tube are reflected by the infrared reflecting film formed on the surface of the intermediate tube and returned to the arc tube, thereby increasing the temperature of the wall of the arc tube and improving the luminous efficiency. In addition, since infrared rays do not reach the outer bulb, the temperature rise of the outer bulb is regulated, which has the advantage that the outer bulb can be manufactured from hard glass, etc., which is inexpensive and easy to process.

(Problem to be Solved by the Invention) However, in the case where the intermediate tube formed with the infrared reflective film is housed in the outer tube as described above, the temperature of the intermediate tube increases significantly, and the temperature does not reach more than 500'C. However, there are concerns about thermal deterioration of the infrared reflective film, and there is also concern about blackening of the outer tube due to scattering of oxides.

The present invention was made based on the above circumstances, and its purpose is to provide a high-pressure metal that can suppress the temperature rise of the infrared reflective film and prevent thermal deterioration of the infrared reflective film and blackening of the outer tube. The aim is to provide a steam discharge lamp.

[Structure of the Invention] (Means for Solving the Problems) The present invention is characterized in that the outer surface of the intermediate tube on which the infrared reflective film is formed is brought into contact with the inner surface of the outer tube over substantially the entire surface.

(Function) According to the present invention, since the outer surface of the intermediate tube contacts the outer tube over almost the entire surface, the heat of the intermediate tube is released to the outside through the outer tube, thereby reducing the temperature rise of the intermediate tube and the infrared reflecting film. It can be suppressed. Therefore, thermal deterioration of the infrared reflective film and blackening of the outer tube can be prevented.

(Example) The present invention will be described below based on a first example shown in FIG.

The drawing shows a 150W type high-pressure sodium lamp, and in the drawing, 1 is an outer tube. This outer tube 1 is made of hard glass with an outer diameter of 27 cm and a wall thickness of 1 cm, and has crush sealing parts 2, 2 at both ends.
It is formed.

An arc tube 3 is housed in the outer tube 1 .

The arc tube 3 is a bulb formed from a ceramic tube such as polycrystalline alumina or single crystal alumina with an outer diameter of 8 mm, and the end of the bulb is closed with a closing wall, and an electrode support structure 4 is attached to this end.
．． Electrode 5.5 is sealed via 4.

The electrode 5.5 is composed of an electrode shaft made of tungsten and an electrode coil made of tungsten wound around the electrode shaft.

The arc tube 3 is filled with sodium as a luminescent metal, mercury as a buffer gas metal, and a starting rare gas.

The electrode support structures 4.4 are each welded to holders 6.6 made of niobium wire with a wire diameter of about 0.41 mm, and these holders 6.6 are connected to support wires 7.7.

The support wires 7.7 are formed of molybdenum wires with a wire diameter of about 0.7 mm, and one end is connected to each power supply line 8.8. These power supply lines 8.8 hermetically pass through a crushing seal 2.2 formed at the end of the outer tube 1 and are led out.

An intermediate tube 10 is housed within the outer tube 1.

The intermediate tube 10 is made of quartz glass and surrounds the arc tube 3, and has an infrared reflecting film 11 formed on its outer or inner surface (in this embodiment, the outer surface).

The infrared reflecting film 11 is formed by stacking a TiO thin film and a 5in2 thin film in multiple layers, and transmits visible light but reflects infrared rays.

The intermediate tube 10 is fitted into the outer tube 1 so that the outer surface, and therefore the infrared reflective coating 11, is in almost full contact with the inner surface of the outer tube 1, and the end portion is connected to the support wire 7.7. It is supported in a pressed manner and is therefore supported in an axially immovable manner within the outer tube 1 .

Note that 13 is a support plate that mechanically holds the feeder line 8.8 at the center of the outer tube 1, and 14 is a getter.

The operation of the high-pressure sodium lamp having such a configuration will be explained.

During lighting of the lamp, infrared rays emitted from the arc tube 3 are reflected by a film 11 formed in the intermediate tube 10 that transmits visible light and reflects infrared rays, and therefore the reflected infrared rays are returned to the arc tube 3 and are reflected by the infrared rays. Since the tube wall of the arc tube 3 is heated, luminous efficiency is improved and color rendering properties are also improved.

In this case, since the infrared rays are reflected by the infrared reflecting film 11 formed on the intermediate tube 10, the infrared rays do not reach the outer tube 1, or the amount that reaches the outer tube 1 is small, thus suppressing the temperature rise of the outer tube 1. be able to.

Specifically, it has been confirmed that the temperature of the outer tube 1 can be regulated to 300'C or less, and therefore the outer tube 1 can be manufactured from hard glass that is inexpensive and easy to process.

Further, since the intermediate tube 1o is housed in the outer tube 1, and the infrared rays reflected by the infrared reflecting film 11 pass therethrough, the temperature of the intermediate tube 1o increases considerably even if it does not reach 500° C. or more.

In this embodiment, since the outer surface of the intermediate tube 10 is brought into contact with the inner surface of the outer tube 1 over almost the entire surface, the heat of the intermediate tube 10 is released to the outside through the wall of the outer tube 1.

Therefore, the temperature rise of the intermediate tube 10 and the infrared reflective film 11 is suppressed. Therefore, thermal deterioration of the infrared reflective film 11 is prevented, and since no scattering occurs, blackening of the outer tube 1 can be prevented.

Further, the intermediate tube 10 in the above embodiment has a cylindrical shape,
It can be obtained by forming an infrared reflective film 11 on the outer surface of a long quartz tube in advance and cutting it into a predetermined length. Therefore, the intermediate tube 1o on which the infrared reflective film 11 is formed can be easily obtained and manufactured at low cost.

Since such an intermediate tube 10 only needs to be inserted into the outer tube 1, it is easy to manufacture a high-pressure sodium lamp.

Note that the present invention is not limited to the above embodiments.

That is, the first embodiment is applied to a double-end sealed high-pressure sodium lamp, but the lamp structure is a single-sealed type with a cap 20 provided at one end, as in the second embodiment shown in FIG. It may also be a lamp.

Note that 21... is a tube support wire that restricts the intermediate tube 1o from moving in the axial direction, and is welded to the support wire 7.7.

Furthermore, the present invention is not limited to high-pressure sodium lamps, but can also be applied to metal halide lamps.

[Effects of the Invention] As explained above, according to the present invention, while the outer surface of the intermediate tube is in contact with the outer tube over almost the entire surface, the heat of the intermediate tube is released to the outside through the outer tube. It is possible to suppress the temperature rise of the formed ultraviolet reflection film. Therefore, thermal deterioration of the infrared reflective film and blackening of the outer tube can be prevented.

[Brief explanation of the drawing]

FIG. 1 shows a first embodiment of the present invention, which is a sectional view of a high-pressure sodium lamp, and FIG. 2 shows a second embodiment of the invention, which is a sectional view of a high-pressure sodium lamp. 1... Outer tube, 3... Arc tube, 0... Intermediate tube, 1... Infrared reflective film.

Claims (1)

[Claims] A luminescent metal, a buffer metal, and a starting rare gas are sealed in an arc tube equipped with electrodes, and this arc tube is housed in an outer bulb, and a luminescent metal is placed between the arc tube and the outer bulb. In a high-pressure metal vapor discharge lamp, an intermediate tube surrounding the tube is provided, and the intermediate tube is provided with an infrared reflective film, and the outer surface of the intermediate tube on which the infrared reflective film is formed is substantially entirely in contact with the inner surface of the outer bulb. A high-pressure metal vapor discharge lamp characterized in that the lamps are connected to each other.